The faster moving of two planets in aspect; the significator is said to aspect the slower moving planet (promittor). Also used in reference to the planetary ruler of a house, matter, object or person. See also promittor.
In Natal Astrology, the planet which rules the Ascendant. In Horary, the planet ruling the house governing the matter or person in question. In Directions, the Significator can only be Sun, Moon, Ascendant or Mid-Heaven (according to Sephariel).